In its offensive launched Wednesday on U.S.-backed Kurdish fighters in northeast Syria, Turkey's military relies on several Syrian rebel groups who have been trained by the Turkish military.
The offensive, codenamed "Operation Peace Spring," is aimed at removing fighters affiliated with the Kurdish People's Protection Units (YPG) from areas near the Syria-Turkey border, Turkish officials said.
The Syrian National Army (SNA), a Turkish-backed rebel group active in parts of northern Syria, is the main group that is participating in the Turkish-led offensive in northeast Syria.
Youssef Hammoud, a spokesman for the SNA, told pro-opposition media in Syria that rebel fighters have been positioned for days near Syrian towns that the Turkish military intends to capture in its ongoing offensive.
Salim Idris, an SNA commander, said Monday in a press conference in Turkey that his group "is standing in strength, resolve and support with our Turkish brethren in Turkey" in their military operation into Syria.
While Turkish Special Forces are leading the assault, nearly 14,000 Syrian rebels are supporting the operation, which is expected to target Kurdish fighters in at least three locations in northeast Syria, experts said.
"Some of the rebels have been deployed on the border from the Turkish side, and others already have begun entering parts of northeast Syria," said Ahmed Rahal, a former Syrian military general who is now a military analyst based in Istanbul.
He said rebel groups such as Sultan Murad Division, al-Hamzat Division, Ahrar al-Sharqiya and several smaller factions will play a major role in capturing towns that currently are under the control of the Syrian Democratic Forces (SDF), a military alliance of Arab and Kurdish fighters.
The Sultan Murad Division was established in 2013. Experts say it has been receiving direct financial, military and logistic support from the Turkish military. Most of its fighters are ethnic Turkmen. It was primarily based in the Syrian city of Aleppo before Syrian regime troops retook the city in 2016.
The Hamzat Division, founded in April 2016 in Turkey, was one of the first Turkish-backed Syrian groups that entered the Syrian town of Jarablus in 2017 alongside the Turkish military.
The Ahrar al-Sharqiya group, founded in 2016, comprises mostly of fighters from the eastern Syrian province of Deir Ezzor. Some of its fighters are former members of the powerful Islamist rebel group Ahrar al-Sham.
Rahal told VOA that Turkey is planning to use these Syrian rebel fighters to guard towns retaken from Kurdish fighters in a border area that stretches for 160 kilometers.
The offensive comes days after U.S. President Donald Trump ordered the withdrawal of U.S. troops from areas near the Syria-Turkey border. The U.S. has about 1,000 troops in northeast Syria that have been instrumental in the fight against the Islamic State (IS) terror group.
SDF numbers are unclear
While it is still unclear how many SDF fighters have been deployed to battle Turkish forces and their allied Syrian rebels, SDF officials have stated to VOA they have at least 85,000 fighters who have been trained and equipped by the U.S.-led coalition to defeat IS. SDF has not indicated whether all of its forces would participate in defending the region against the Turkish incursion.
The multi-ethnic SDF includes several groups, including the YPG, YPJ (women-only force), the Syriac Military Council (a Christian armed group), Jaish Thuwar Deir Ezzor , and several local military councils that are in charge of cities and towns throughout north and eastern Syria.
Turkey views the YPG, the main fighting force within SDF, as a terrorist group that has ties with the Turkey-based Kurdistan Workers' Party (PKK), a Turkey, U.S. and EU designated terror group.
The United States makes a distinction, however, between the two Kurdish groups, backing the YPG in its fight against IS militants.
Despite a U.S.-Turkish agreement in August to establish a buffer zone in northern Syria between Turkish forces and Kurdish YPG fighters, Turkey had been threatening for months to invade Syria's northeast.
Analysts said most of the Syrian rebels involved in the Turkish offensive have been using social media to mobilize their supporters and to justify their alliance with the Turkish military.
"Most of them are extremist groups that have participated in battles against the SDF in the past," said Sadradeen Kinno, a Syrian researcher who closely follows militant groups in Syria.
He told VOA the main objective for these rebel forces is to make certain that U.S.-backed forces "such as the SDF have no role in the future of Syria."
The SNA was founded this month after a merger among several Turkish-backed Syrian rebel groups, Turkish and Syrian media said.
"Turkey has founded the SNA to present it as a disciplined force after major abuses they committed in areas such as Afrin," analyst Kinno said.
In March 2018, Turkish military and allied Syrian rebels took control of the Kurdish-majority town of Afrin in northwestern Syria. The two-month-long offensive dislodged YPG fighters from Afrin.
U.N. organizations and human rights groups have often said that rebel forces have carried out systematic violations against Kurdish civilians in Afrin.
Rights groups fear that the new Turkish operation could further destabilize a region already devastated by the eight-year civil war.
"A Turkish assault on northeastern Syria, a country ravaged by war and a humanitarian crisis, would likely cause massive civilian harm and further displacement of hundreds of thousands of civilians," said Philippe Nassif, advocacy director for the Middle East and North Africa at Amnesty International.
He told VOA that "a new refugee crisis on top of the one that has already led to over 5 million Syrians fleeing their country would be a tragedy of epic proportions."